======================================
| [   87.220956][    C1] page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)
| [   87.221605][    C1] ------------[ cut here ]------------
| [   87.221772][    C1] kernel BUG at include/linux/mm.h:1140!
| [   87.221935][    C1] Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN NOPTI
[   87.222559][    C1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 87.222992][ C1] RIP: 0010:__free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 87.223210][ C1] Code: 0f 94 c3 e9 ba fe ff ff 48 c7 c6 a0 18 f8 a1 4c 89 e7 e8 df bf f4 ff 90 0f 0b 48 c7 c6 40 29 f8 a1 4c 89 e7 e8 cd bf f4 ff 90 <0f> 0b 48 89 ef e8 72 03 09 00 e9 c5 fe ff ff e8 98 03 09 00 e9 35
All code
========
   0:	0f 94 c3             	sete   %bl
   3:	e9 ba fe ff ff       	jmp    0xfffffffffffffec2
   8:	48 c7 c6 a0 18 f8 a1 	mov    $0xffffffffa1f818a0,%rsi
   f:	4c 89 e7             	mov    %r12,%rdi
  12:	e8 df bf f4 ff       	call   0xfffffffffff4bff6
  17:	90                   	nop
  18:	0f 0b                	ud2
  1a:	48 c7 c6 40 29 f8 a1 	mov    $0xffffffffa1f82940,%rsi
  21:	4c 89 e7             	mov    %r12,%rdi
  24:	e8 cd bf f4 ff       	call   0xfffffffffff4bff6
  29:	90                   	nop
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	48 89 ef             	mov    %rbp,%rdi
  2f:	e8 72 03 09 00       	call   0x903a6
  34:	e9 c5 fe ff ff       	jmp    0xfffffffffffffefe
  39:	e8 98 03 09 00       	call   0x903d6
  3e:	e9                   	.byte 0xe9
  3f:	35                   	.byte 0x35

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	48 89 ef             	mov    %rbp,%rdi
   5:	e8 72 03 09 00       	call   0x9037c
   a:	e9 c5 fe ff ff       	jmp    0xfffffffffffffed4
   f:	e8 98 03 09 00       	call   0x903ac
  14:	e9                   	.byte 0xe9
  15:	35                   	.byte 0x35
[   87.223915][    C1] RSP: 0018:ffffc900001bfcb0 EFLAGS: 00010246
[   87.224171][    C1] RAX: 000000000000003e RBX: 0000000000000000 RCX: 1ffffffff457b43c
[   87.224462][    C1] RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001
[   87.224778][    C1] RBP: ffffea00001e4674 R08: 0000000000000000 R09: fffffbfff457b43c
[   87.225135][    C1] R10: 0000000000000003 R11: 205d314320202020 R12: ffffea00001e4640
[   87.225462][    C1] R13: ffffc900001bfd78 R14: 0000000000000000 R15: 0000000000000002
[   87.225744][    C1] FS:  0000000000000000(0000) GS:ffff888036080000(0000) knlGS:0000000000000000
[   87.226090][    C1] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   87.226350][    C1] CR2: 00007fea14024008 CR3: 0000000005984003 CR4: 0000000000772ef0
[   87.226642][    C1] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[   87.226976][    C1] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[   87.227300][    C1] PKRU: 55555554
[   87.227458][    C1] Call Trace:
[   87.227622][    C1]  <TASK>
[ 87.227749][ C1] ? die (arch/x86/kernel/dumpstack.c:421 arch/x86/kernel/dumpstack.c:434 arch/x86/kernel/dumpstack.c:447) 
[ 87.227942][ C1] ? do_trap (arch/x86/kernel/traps.c:156 arch/x86/kernel/traps.c:197) 
[ 87.228112][ C1] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 87.228359][ C1] ? do_error_trap (./arch/x86/include/asm/traps.h:58 arch/x86/kernel/traps.c:218) 
[ 87.228584][ C1] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 87.228766][ C1] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 87.228995][ C1] ? handle_invalid_op (arch/x86/kernel/traps.c:256) 
[ 87.229207][ C1] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 87.229408][ C1] ? exc_invalid_op (arch/x86/kernel/traps.c:315) 
[ 87.229606][ C1] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:621) 
[ 87.229817][ C1] ? __free_pages (./include/linux/mm.h:1140 ./include/linux/mm.h:1138 mm/page_alloc.c:4819) 
[ 87.230046][ C1] ? rcu_do_batch (kernel/rcu/tree.c:2567) 
[ 87.230264][ C1] neigh_hash_free_rcu (net/core/neighbour.c:554) 
[ 87.230481][ C1] rcu_do_batch (kernel/rcu/tree.c:2567) 
[ 87.230719][ C1] ? __pfx___lock_release (kernel/locking/lockdep.c:5477) 
[ 87.230922][ C1] ? __pfx_rcu_do_batch (kernel/rcu/tree.c:2491) 
[ 87.231131][ C1] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4339 kernel/locking/lockdep.c:4406) 
[ 87.231415][ C1] rcu_core (kernel/rcu/tree.c:2825) 
[ 87.231575][ C1] handle_softirqs (kernel/softirq.c:554) 
[ 87.231819][ C1] ? __pfx_run_ksoftirqd (kernel/softirq.c:920) 
[ 87.232034][ C1] run_ksoftirqd (kernel/softirq.c:411 kernel/softirq.c:928 kernel/softirq.c:919) 
[ 87.232276][ C1] smpboot_thread_fn (kernel/smpboot.c:164 (discriminator 3)) 
[ 87.232494][ C1] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 87.232713][ C1] ? __pfx_smpboot_thread_fn (kernel/smpboot.c:107) 
[ 87.232926][ C1] kthread (kernel/kthread.c:389) 
[ 87.233102][ C1] ? __pfx_kthread (kernel/kthread.c:342) 
[ 87.233314][ C1] ret_from_fork (arch/x86/kernel/process.c:147) 
[ 87.233525][ C1] ? __pfx_kthread (kernel/kthread.c:342) 


Finger prints:
__free_pages:neigh_hash_free_rcu:rcu_do_batch:rcu_core:handle_softirqs